i'm the same way josh.. stricky used to love jumping.. i was all about lap times... and jumps were never the most confident part of the track for me either..
i went through the same arm pump problem you're having now, and that was 90% of it for me.. once i learned to relax when jumping, it really helped the arm pump.. may sound dumb, but i used to yell "woohoo!" under my helmet over the jumps.. helped me learn to relax a little.
once you're comfortable over the jumps, we can talk about the whooped out 4th gear straightaways.. those were my favorite FO SHO and another excellent arm pump creator!
stricky used to laugh at me cause when we would ride together, that's where i would blow by him. he used to tell me that the back of my bike was just swapping left and right all over the place and it looked crazy! man, i just loved the feeling of coming around the corner before the long whooped straight, jumping the small double right out of the corner in 2nd gear then clicking up to 4th in the air and just pinning it in the air .. landing, and just shooting through the whoops... what a rush!!!! 5-6 laps of that and my arms were TOAST!